If your goldfish has white bumps, called tubercles, on each gill, then the fish is definately a male. However, just because one fish has reached sexual maturity doesn't mean all the others have. Fish mature at different rates, much like people. Just because they are the same AGE doesn't mean they have all matured. It may take longer for others to reach this point. If your fish Hazel is demonstrating spawning behavior by pursuing your other fish, bumping into them against the walls and being aggressive, this means that the fish being pursued are most likely females.
Hope this helps.